<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .main{
            width: 400px;
            height: 400px;
            background-color: gray;
            margin: 0 auto;
            margin-top: 100px;
            border: 1px orange solid;
            display: flex;
           flex-direction: row;
           
        }
        .main div{
            width: 50px;
            height: 50px;
            border: 1px green solid;
        }
    </style>
</head>
<body>
    <div class="main">
     <div>1</div>
     <div>2</div>
     <div>3</div>
     <div>4</div>
     <div>5</div>
    </div>
    
</body>
</html>